1. Field of the Invention
The technical field of the present invention relates to a semiconductor device and a method for manufacturing the semiconductor device.
Note that semiconductor devices mean elements and devices in general which function by utilization of semiconductor characteristics.
2. Description of the Related Art
In order to realize high performance (high speed and low power consumption) of an integrated circuit, miniaturization of a transistor has been underway.
In the case where a field effect transistor (a FET) is used as a transistor and miniaturization is performed, miniaturization of a transistor is pursued through the reduction of a channel length obeying a scaling law, the thinning of a gate insulating film, and the like.
As the miniaturization proceeds, a short channel effect becomes apparent. In order to suppress such a short channel effect, a threshold voltage of a transistor is controlled by adjusting an impurity concentration in a semiconductor layer. However, the adjustment of the impurity concentration in the semiconductor layer leads to the reduction of ON current (current drive capability) which is caused by the impurity scattering of carriers and the like. Therefore, it is very advantageous to reduce the resistance of each member (a source region, a drain region, a wiring, and the like) which is included in the transistor in advance. Note that as the miniaturization proceeds, the reduction of the ON current, which is caused by the resistance of each member included in the transistor, becomes more pronounced.
As an example of a field effect transistor, Patent Document 1 discloses a field effect transistor in which a single crystal semiconductor layer is provided over an insulating layer using an SOI (silicon on insulator) technique. In the field effect transistor with an SOI structure in Patent Document 1, a silicide region is formed using an alloy of metal and a semiconductor material in a source region and a drain region, so that the reduction of contact resistance between the field effect transistor and a wiring is realized.